Oat Flour Enriched with Nectarine Powder of Bulgarian Origin Antioxidant Activity, Microbiological and Moisture Sorption Characteristics

Adelina Vasileva, Albena Durakova, Milena Dimitrova-Dicheva, Zhivka Goranova, Hristo Kalaydzhiev and Kliment Georgiev

Abstract: Two regional food products were evaluated to create a flour mixture intended for the production of sponge cake. The functional mixture flour consists of oats flour and nectarine powder of Bulgarian origin. The current scientific research presents the physicochemical composition, antioxidant activity, microbiological, and sorption characteristics of the new flour mixture. The performed analysis on the physicochemical parameters were protein 9.98 g, total carbohydrates 74.40 g, total lipids 3.71 g, ash content 3.49 g and crude fibers 6.21 g, calculated on a dry matter basis of 90.82%. The antioxidant activity was determined using the DPPH, ABTS, FRAP, and CUPRAC methods. All microbiological parameters, namely the total count of mesophilic aerobic and facultative anaerobic microorganisms, yeasts and molds, Escherichia coli, Salmonella spp., coagulase-positive staphylococci, and coliforms, were under permissive norms and no pathogenic organisms were detected. Sorption characteristics, including equilibrium moisture content and monolayer moisture content, were investigated at three different temperature – 10°C, 25°C and 40°C and water activities in the range of 0.1 to 0.9 following the static-gravimetric method. Estimation of obtained sorption isotherms was performed with a modified three-parametric model of Halsey, Oswin, Henderson and Chung-Pfost, evaluating with criteria of suitability models, namely average relative error (P, %) and moisture standard error (SEM). BET equation was linearized for obtaining the monolayer moisture content values.

Keywords: antioxidant activity; flour mixture; monolayer moisture content; nectarine; oats; sorption isotherms

Date published: 2022-12-09